Electrical transmission apparatus.



ELECTRICAL TRANSMISSION APPARATUS. APPLICATION IILBD 113.28. 190a.

. PATENTED JAN. 21, 1908.- S. EVERSHBD.

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No. 877,312. PATENTED JAN. 21, 1908. S. EVERSHED.

ELECTRICAL TRANSMISSION APPARATUS. APPLICATION FILED PEB.28.1906.

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0-00 Q -Q MUN No. 877,312. PATENTED JAN. 21, 1908. J ELECTRICALTRANSMISSION APPARATUS.

S. EVBRSHED.

APPLIOATION FILED FEB. 28. 1906.

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No. 877,312. PATENTED JAN. 21, 1908. S. EVERSHED. ELECTRICALTRANSMISSION APPARATUS.

APPLICATION FILED FEB.28.1906.

6 SHEETSSHEBT 4.

No. 877,812. PATENTED JAN. 21, 1908. S. EVERSHED. ELECTRICALTRANSMISSION APPARAT APPLICATION FILED FEB.28.1906.

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No. 877,312. PATENTED JAN. 21, 1908. S. EVERSHED. ELECTRICALTRANSMISSION APPARATUS.

APPLICATION FILED FEB.28, 1906.

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IHI. JJ

UNITED STATES PATENT ornron SYDNEY EVERSHED OF OHISWIOK, ENGLAND,ASSIGNOR TO HIMSELF AND EVERSHED AND VIGNOLES LIMITED, OF LONDON,ENGLAND, A CORPORATION.

ELECTRICAL TRANSMISSION APPARATUS.

Specification of Letters Patent.

Patented Jan. 21,1908.

Application filed February 28. 1906- derial No. 303-556- subject of theKing of Great Britain and Ireland, residing at Chiswick, county ofMiddlesex, England, haveinvented new and useful Improvements inElectrical Transmission Apparatus, of which the following is aspecification. My invention is applicable to any purpose requiringdistant mechanisms to be moved automatically orat will by definiteamounts,

and isparticularly applicable to ships tele graphs, steering gear, andother means of communication or control required on board ship; to traindespatching telegraphs, mining telegraphs, engine room or power housetelegraphs and other purposes, requiring a similar correspondence in themotion or position of two or more pieces of mechanism.

My invention is based upon a" principle analogous to the VVheatstonebr1dge,an electric motor taking the place of the galvanometer in thebridge. This principle as heretofore applied for repeating movements ata distance, wastes a large amount of energy in comparison with theuseful work done, and has the further defect that owingto the friction,hysteresis and other retarding forces acting on the bridge motor, thecorrespondence between the transmitting and receiving devices is by nomeans exact.

The objects of my invention are to make the correspondence between thetransmitting and receiving appliances as precise as the limitations ofworkmanship will permit to lessen the waste of electrical energy in thenecessary resistances and to lessen the time occupied by the distantmechanisms in movresistance. nected in parallelon the same supplcircuit,

ing 1nto correspondence with the transmitting mechanisms.

In describing my invention I shall assume, as a typical example, that itis to be applied to a simple "telegraph, such as is required fortransmitting orders from the bridge of a ship to the engine room, orfrom the pit head of a colliery to the bottom of the shaft. Thetransmitter will be a multiple point switch adapted to make contact atany one of a number of points upon a subdivided resistance. The receiverwill contain a corresponding switch and a similarly subdivided The tworesistances will be conand thearms of the two switches wi 1 be connected by a wire, hereinafter called the, bal

ancing wire. At the receiver, a motor is inserted in the balancing wireand the switch arm is connected with the motor spindle by suitablegearing. The motor is also geared to a drum or disk upon which therequired orders are marked, only one order at a time being visiblethrough a hole in a dial. in a normal condition the transmitting switchand the receiving switch will stand at corresponding points causing thebalancing .wire to make contact with points on the two resistances whichare at the same potential. Hence no current will flow in the balancingwire and motor. If new the transmitter switch is moved over one or morecontacts and brought to rest at another point, the balance is disturbed,a current w ll flow in the balancing wire and traversing the motor, willcause it to rotate. The motor will then move the'receiving switchtowards a point on the resistance of the same potential as that at whichthe transmitter stands, gradually reducing the balancing current as itdoes so, until the torque due to the current is just insuflicient toovercome the retarding forces acting upon the motor. The receiv: ingswitch arm will therefore fall short of exact correspondence with the.transmitter when the motor stops, and the signal drum willfall short ofthe required osition to a corresponding degree. This fa ling shortof theright position isanalogous to the back lash of gear wheels and is hereinreferred to as the back-lash of the motor. The effect of the motorback-lash is greatly accentuated by the fact that immediately thereceiving switch arm just touches the contact corresponding with that atwhich the transmitter switch stands, the balancing current drops verynearly to zero ;.so that the motor will sometimes stop when the switcharm is al-' most half'a contact breadth shdrt of the proper position,and the signal drum may all short by nearly half the spaces of oneorder.

According to my invention this liability to fall shortv of exactcorrespondence may be eliminated either by the interposition ofadiscontinuous gear between the motor and the signal drum, or by means ofduplicated contacts and auxiliary resistances in the receiver. For thefirst method I use ordinary continuous toothed gearing to connect themotor to the switch, but I cause the motor to drive the signal drum bymeans of any When 1 Harding counter .counter gear illustratedinFig. 3 ofU. S. A.

Patent Specification No. 297670 issued 29th April, 1884 to CyrusChambers, Jr. With this arrangement the motor, after having moved thesignal drum fromone signal to the next, is free to make a certain numberof revolutions, without again moving the 1 drum; and so long as it hasmade rather more than half the number of revolutions that correspondwith a change of one signal, the exact position in which it comes torest has no efiect upon the position of the drum. Hence the motor andswitch arm may fall short of exact correspondence with the transmitterwithout in any way interfe with the position of the drum, which willalways correspond exactly with the transmitter.

For my second method I double the number of subdivisions in the receiverresistance, and duplicate the switch contacts by the insertion of ahalf-way contact between each 1 ally resting at the center of itsbreadth, I insert an auxiliary resistance between each tion.

two successive signal contacts. My object being to maintain the want ofelectrical bal., ance until the switch-arm is not merely touching theright signal contact, but actusignal contact and the point on thereceiver resistance to which it is connected, By making this auxiliaryresistance as much as four or five times the resistance of onesubdivision of the receiver resistance, no appreciable change takesplace in the want of electrical balance when the switch arm bridgesacross from a half-way contact to an adjacent signal contact and hencethe balancin current is maintained at very nearly its ful strength untilthe switch arm has traveled entirely ofl" the half-way contact on to themiddle of the signal contact. To avoid back-lash in the' switch itself,the switch-arm must be made broad enough to more than cover the width ofa signal contact, so that when at rest centrally on any signal contactit very nearly touches the adjacent half-way contacts on elther slde ofthe signal contact. With this arrangement and construction it isimpossible for the switch arm to rest anywhere but on the middle of thesignal contact corresponding with the position of the transmitterswitch; for if it is moved slightly in one direction or the other itcomes into contact with the adjacent halfway contact on one side or theother. The full balancing current then immediately traverses the motorwhich revolves until it has restored the switch to its correct posi- Insome applications of thebridge motor boxes or cases it is essential thatthe energy consumption should be reduced as much as ossible. The currentwhich will flow in the balancing wire when the transmitting andreceiving switches are not on corresponding contacts, 1s a maximum whenthe motor is at rest; and under these conditions it follows the same lawas the current in the galvanometer of a VVheatstone bridge. That is tosay, its value for any given voltage depends very largely upon the valueof the transmitting and receiving resistances, .and the power receivedby the motor is limited by the permissible waste of .ener y in them. Thetorque of the motor may be increased to anyextent at the cost of areduction in its speed of working, but the electrical power received bythe motor can only be increased by increasing the waste of energy in theresistances.

' In order that my invention may be .the better understood, I will nowdescribe it with reference to the accompanying drawings of which vFigure 1 represents my improved receiving mechanism in combination withan ordinary transmitter in which exact correspondence of transmitter andreceiver is secured by the use of a discontinuous gear of the countertype. Fig. 2 shows my improved mechanism, I

in which exact correspondence is secured by the use of intermediatecontacts between the principal, or signal points, together withauxiliary resistances to prevent short circuiting. receiving switch forthe same purpose. Fig.- 4 illustrates the application of my system bywhich several receiving mechanisms may be independently operated bymeans of one sub-dividing reslstance. Fig. 5-illustrates my system whenthe one transmitting mec anism is to be repeated by 'several receivingmechanisms,-

and Fig. 6 shows an alternative arrangement in which the field coils ofthe motor are provided with sub-divided resistance. Fi 7 shows analternative arrangement in w 'ch permanent magnets are used for themotor.

In all these figures, like letters refer to like parts, and it is to beunderstood that in order to illustrate my invention clearly, the drawmgsare in the form of diagrams, and a simosition or motion of Fig. 3 showsa modified form of ple form of indication is shown therein, in I orderthat the relation between the position of the transmittingmand receivingswitches and the correspon g position 0 the indicating mechanism may bereadily understood. -In.all cases, the transmitting switch 5 may either.be worked by hand if it is required to transmit signals, or orders atwill, or it may be connected to any mechanism,

the position of which is to be indicated or reproduced at a distantpoint.

In Fig. 1, A is the transmitting station and B the receiving station. Ishow a transmitting-switch 0 adapted to make contact by means of the arml) with-any one of the contacts of a multiple point switch which isconnected to the sub-dividing points of the transmitting resistance E.These subdividing points are numbered 0 to 9 on the drawing andcorresponding numbers may be indicated by means of a ointer onthe-switch handle. The termina s of the subdivided resistance areconnected to two Wires F and G, hereinafter referred to as the supplywires,

and the switch arm D is'connected by means of a rubbing contact H with awire I, here inatter referred to as the balancing wire. A battery J, orother suitable source of electric energy, is connected at any convenientpoints with the supply wires.

At the receiving station B the sup-ply wires are connected to asubdivided resistance K, which has its subdividing points numbered 0 to9 respectively, connected to a multiple point switch L. The balancingwire circuit after traversing the armature M of an electric motor, bymeans of'the brushes N, O and commutator P, is led to a rubbing contactQ in connection with the switch arm R. The motor armature is cared tothe axle which carries the switc arm R, by

' means of apinion S gearing into a wheel T,

on the axle of which is a second pinion U g'earin into the wheel V, theswitch arm B being ed upon the axle of V. The axle of T and U carries adisk-W, on the lower surface of which a single; tooth X is fixed whichonce in every revolution comes into gear with. the pin Wheel Y, anddrives it forward or backward by the space of two pins Z, whichin theexample taken, is equal to one-tenth of a revolution. The pinwheel axlecarries the indicating device; in

the example taken, this is adisk a having digits or other indicatingdevices marked u on it, one of which is visible at a time tliiough awindow 6 in a dial 0. The gear ratio of U to V must of'course correspondwith that of the disk W to the pin-wheel Y. I show the exciting coils dof the motor.

I connected to the supply wires F and G; this being the simplestmeans ofobtaining the necessary magnetizing force. But where it is necessary toeconomize power 1 wind the subdividing resistance K in a form suitablefor field coils as shown in Fig. 6, and arrange them on the field magnetof the motor, so that they may serve both as the subdividedresistanceland as the field-exciting coils. It

may happen that this last arrangementis impracticable, either by reasonof want' of space on the motor, or of the complicated connectionsrequired, in which case 1 may use permanent magnets for providing themag wheel is eilected with a minimum of friction,

while when not so engaged the pin-wheel is ellectually locked by meansof the locking ring W In Fig. 1 the transmitting and receiving switchesare standing on corresponding switch contacts, namely those connectedwith point No. 6 on the transmitting resist ance, and point No. 6 on thereceiving re sistance. These two points being at: the same potential, nocurrent traverses the balancin wire or armature and the receivingmechanism is at rest, the indicating device being securely locked by thecounter gear. If, now, the transmitting switch is moved to anotherpoint, for example poirit No. 8, the potential at the transmitting endof. the balancing wire will be two points in excess of the potential atpoint No. 6 at the receiving end, and hence a current will traverse themotor and drive it in a counter clock-wise direction until the receivingswitch arm stands upon contact point No. .8. At this 'moment thebalancing current will fall to zero and the friction and other retardingforcesacting upon the motor will bring it tothe pin-wheel, so that thelatter will have moved forward by two steps or two-tenths of avrevolution, and the digit 8 will have been brought to the window I).

It will be seen that the exact position in which the motor comes to restdoes not afiect the position of the pin wheel and indicating device; solong as the single tooth X has passed through its engagement with thepin whee], it isrof no importance precisely where it comes to rest, andhencethe position of the indicating device corresponds exactly with theposition of the transmitting switch C, and the repetition of ,themovements of the transmitting mechanism is independent of the precisevalue of thelriction, hysteresis, and other'retarding'influences actingupon the receiving mechanism, and independent travers'e'the outer ringof in one ring and the other.

rincipal points, and the receiving switch likewise has intermediatecontacts. With this arrangement it is necessary to insert auxiliaryresistances e in the Wires connecting the-principal potential points ofthe receiving resistance with the principal con tacts of the switch, inorder that when the switch arm R projects over two. contacts it shallnot short-circuit that section of the receiving resistance which isbetween the two points in question. The effect of this arrangement 1sthat it is impossible for the motor to come to rest unless the switcharm R In order that the fall of potential along the resistance K shouldnot be materially changed when the arm R touches two contacts, theauxiliary resistance must be at least four or five times as great as theresistance ,of one principal subdivision in the receiving resistance.The precision of indica tion with this modification depends on the widthof the contact arm R; this is made just so wide that when standing onany principal contact it very nearly touches the ad jacent intermediatecontacts on either side of it, so that if it moves by a very smallamount in either direction it comes into contact with one or other ofthem, and the motor thereu on restores it to its correct position.

In ig; 3 I show a modified form of switch for securing the same exactcorrespondence without the necessity for doubling the number ofsubdivisions in the 'a'nce. In this modification I arrange theprincipal, contacts of the switch in two concentric rings, the contactsbeing alternately I then provide two contact arms f and g, f beingadapted to contacts, and g the I inner-ring. These arms are attached toan acts on exactly insulating support It and they are electricallyconnected to each other by means of an.-auxiliary resistance e.- Thebalancing wire is connected to the middle point of this auxiliaryresistance by means ofthe rubbing contact Q and'contact Dummy or blankcontact plates 1' are fixed in between the working or principal.contacts in order to enable the switch arms to travel smoothly from onecontact to the next. This switch the same principle. as that in theposition shown in shown in Fig. 2;

arm f is making contact wit 3, the switch contact N 0.

receiving resistthrough three windows in a oint/No. 6, while switch arm9 stands on a blank contact, and is therefore insulated; hence thebalanci wire is connected to point N o. 6 through half of the auxiliaryresistance. If, now, the switch is moved by a very smallamount in onedirection or the other so that switch arm 9 touches a neighboringprincipal contact (say for example 5), that section of the receivingresistance which lies between, points 'Nos. 5 and 6 is shunted by theauxiliary resistance 6 and hence the potential at the center of theauxiliary resistance is midway between the potentials of points 5 and 6;so that, assuming the transmitting switch to be standing at the pointscorresponding to No. 6 a current will flow throughthe balancing wire andmotor, and the receiving switch will-be. restored to its correctposition with switch arm 9 at rest exactly on the center of the blankcontact, and not incontact either with contact 5 or contact 7.

It will be seen that the auxiliary resistance in Fig. 3 is made to servetwo functions, namely, to provide a potential point midway 90 betweenany two principal points, and also a to avoid short-circuiting anysection of the receiving resistance.

In Fig. 4, I show how several transmitting switches having independentswitch arms D D and D may be made to transmit from a single subdividedtransmitting resistance, by

a single pair of supply wires, F G throng several balancing wires I Iand I to several and which work on a single receiving re-. sistance;these receiving switches being in dependently controlled by means ofmotor armatures M M and M Such an arrangement as this forms a convenientmeans of transmitting any independent series of orders from one positionto another; for example, with three motors I may control threeindicating disks or drums, upon each of which the digits 0-to 9 aremarked andshown row in a dial, so that an desired number from 0 to 999may be exhi ited at the receiv' g station by manipulating the threetransmitting switch handles'C C and 0 tion. V

5, I show how a single transmitting apparatus may be made tosimultaneously control a number of recei f mechanisms placed atreceiving stations 1 B B 'etc.

his diagram, being self-explanatory, needs no description, but itillustrates the means I employ for providing a tell-tale by which theperson who is" operating the transmitting atthe transmitting sta- 115apparatus can besure that all the receivers have res onded accurately.This is easily y the insertion of any suitable detector galvanometer kin the circuit of the balancing wire.

When a number of transmitting switches indeppndent receiving switch armsR R 100' are employedfor signaling a number composed of several digits,(the several switches corresponding to the units, taps and hundredsdigits in----the number to be transmitted), it. may be preferable toarrange each switch so that it may pass from 9 to withouttraveling backalong the other points.

In other words the balancing wire may be uite suddenly shifted frompotential point 0. 9 to potential point No.0 and until the motor hasattained suflicientspeed an excessive current would traverse it and tendto produce destructive sparkin at the commutator. To avoid this possibiity I may insert I an extra pair of sectionsboth'in the transmitting andreceiving sub-dividing resistances and I have shown 'these in mydrawing. In Figs. 1, 2 and 3 the'twoadditional shown at a: m and-thecorresponding additional sections in, the receiving resistance are shownat'y'y. s

' Having now described my invention what 'I claim anddesire to-secure byLetters Patent is 1 In receiving apparatus for repeating the movementsof a'transmitter, the combinationqf a bridge motor in a balancingcircuit,

a repeating device a subdivided resistance, a multiple point switchconnected to said resistance, gear connecting the repeating device andthe switch to the bridge motor and means for securing exactcorrespondence of the receiver with the'transmitter, substantially asdescribed. s

2. In receiving apparatus for repeating the I movements of atransmitter. the combina- .tionof abridge motor in a balancing circuit,a repeating dev ce, a subdivided resistance, a

multiple point switch adapted to make contact with any subdivision ofthe said resistance, gear connecting the repeating device and the switchto the bridge motor, and auX- iliary resistance adapted to secure exactcorrespondence of the receiver with the trans inittersubstantially asdescribed.

3. In receiving apparatus for repeating the movements of a transmitterthe combination of a bridge motor, a repeating device, a

subdivided resistance, a multiple point switch adapted to make contactwith any subdivision of the said resistance, gear connecting therepeating device and the switch to the bridge motor, andauxiliaryresistances adapt ed to secure exact correspondence of thereceiver with the transmitter, substantially as I described. sections inthe transmitting resistance are 4. In receiving apparatus for repeatingthe movements of a transmitter the combination of a bridge motor, arepeating device, a subdivided resistance having intermediate potentialpoints between the principal 1points a multiple point switch adapted toma e contact with any one of the principal orintermediate potentialpoints, gear connecting the repeating device and the switch tothe'bridge motor, and auxiliary resistance between the intermediatepotential points and the switch adapted to secure exact correspondenceof the receiver with the transmitter, substantially as described. f J Intestimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

-' SYDNEY EVERSHED.

Witnesses: l

Rronnu) A. HOFFMANN,. 7 CHARLES CARTER.

